Update cpp/ql/lib/semmle/code/cpp/commons/StringConcatenation.qll

Co-authored-by: Mathias Vorreiter Pedersen <mathiasvp@github.com>

Author: bdrodes

cpp/ql/lib/semmle/code/cpp/commons/StringConcatenation.qll

@@ -5,7 +5,7 @@
 import cpp
 import semmle.code.cpp.models.implementations.Strcat
 import semmle.code.cpp.models.interfaces.FormattingFunction
-import semmle.code.cpp.dataflow.new.DataFlow
+private import semmle.code.cpp.dataflow.new.DataFlow
 
 class StringConcatenation extends Call {
   StringConcatenation() {